show that:
1+q∫10x1−qxdx=∞∑k=0(qk+1)k⋯⋯(1)
I kown prove following this
∫10x−qxdx=∞∑n=0qn(n+1)n+1
note that
∫10x−qx=∫10eqxln1xdx=∞∑n=0qnn!∫10xnlnn1xdx
let ln1x=t⟹∫10xnlnn1xdx=∫∞0e−(n+1)ttndt=Γ(n+1)(n+1)n+1
so
∫10x−qxdx=∞∑n=0qn(n+1)n+1
But this (1) I can't prove it,Thank you everyone.
Answer
The proof goes along the same lines
∫10x1−qxdx=∫10xe−qxdx=∫10x∞∑n=0(qxlnx−1)nn!dx=∞∑n=0qnn!∫10xn+1lnnx−1dx{lnx−1=t}=∞∑n=0qnn!∫0+∞e−(n+1)ttn(−e−t)dt=∞∑n=0qnn!∫∞0e−(n+2)ttndt{(n+2)t=s}=∞∑n=0qnn!∫∞0e−s(n+2)−nsn(n+2)−1ds=∞∑n=0qn(n+2)n+1
Thus
1+q∫10x1−qxdx=1+q∞∑n=0qn(n+2)n+1=1+∞∑n=0qn+1(n+2)n+1{k=n+1}=q0(0+1)0+∞∑k=1qk(k+1)k=∞∑k=0(qk+1)k
No comments:
Post a Comment